1. Field of the Invention
The present invention relates generally to a rotor of a rotating electric machine and, more particularly, to a rotor of an alternating current (AC) generator or motor in which the rotor includes a pair of pole core members having a plurality of claw-shaped magnetic poles extending along an axial direction of the rotor at regular intervals around the rotor, wherein the claw-shaped magnetic poles are directed face to face from the individual pole core members and engaged with one another as if surrounding a rotor coil.
2. Description of the Background Art
A construction of a rotor of a conventional rotating electric machine to which the invention is directed is shown in Japanese Laid-open Patent Publication No. 2001-86715, for instance. According to the Publication, the rotor includes a rotor coil and a pair of pole core members having a plurality of claw-shaped magnetic poles extending like claws along an axial direction of the rotor at regular intervals around the rotor. The rotor is constructed by fitting the pole core members on a rotary shaft with the claw-shaped magnetic poles of the two pole core members directed face to face from front and rear sides and engaged with one another so that the claw-shaped magnetic poles surround the rotor coil, wherein a magnet which produces a magnetic field oriented in a direction opposite to the direction of a magnetic flux formed between two adjacent claw-shaped magnetic poles is located between side surfaces of the oppositely directed two adjacent claw-shaped magnetic poles. The rotating electric machine (AC generator or motor) includes the rotor thus constructed and a stator located to surround the rotor, the stator including a stator core on which a stator coil is wound, as illustrated in the aforementioned Patent Publication.
When the pole core members are excited by the rotor coil in this construction, the claw-shaped magnetic poles on one side are magnetized as north (N) poles and the oppositely directed claw-shaped magnetic poles on the other side are magnetized as south (S) poles. As the magnets which produce magnetic fields oriented in directions opposite to the directions of the magnetic fluxes formed between the adjacent claw-shaped magnetic poles are situated between the side surfaces of the oppositely directed adjacent claw-shaped magnetic poles, the number of lines of ineffective magnetic fluxes between the side surfaces of the adjacent claw-shaped magnetic poles is decreased and the number of lines of magnetic fluxes extending from outer peripheral surfaces of the claw-shaped magnetic poles toward the stator is increased.
One construction proposed in the aforementioned patent Publication No. 2001-86715 employs reinforcing members having a generally M-shaped cross section for holding magnets on both side surfaces of each claw-shaped magnetic pole. Another construction proposed in the Publication employs reinforcing members having a generally C-shaped cross section for holding magnets on both side surfaces of each claw-shaped magnetic pole. In either of these constructions, the magnets are held at fixed positions on the side surfaces of the claw-shaped magnetic poles by the reinforcing members against a centrifugal force acting on the magnets due to rotation of a rotor, because the reinforcing members are hooked on the inside of the claw-shaped magnetic poles.
As shown in the foregoing discussion, the rotor of the conventional rotating electric machine (AC generator or motor) includes a pair of pole core members having multiple claw-shaped magnetic poles extending like claws along the axial direction of the rotor at regular intervals around the rotor, in which the pole core members are fitted on the rotary shaft with the claw-shaped magnetic poles of the two pole core members directed face to face from front and rear sides and engaged with one another so that the claw-shaped magnetic poles surround the rotor coil. The magnets which produce the magnetic fields oriented in the directions opposite to the directions of the magnetic fluxes formed between the two adjacent claw-shaped magnetic poles are situated between the side surfaces of the adjacent claw-shaped magnetic poles with the magnets supported by the reinforcing members. In this construction, the magnets supported by the reinforcing members are held in the proximity of each claw-shaped magnetic pole.
In the rotor of the conventional rotating electric machine thus constructed, each of the claw-shaped magnetic poles is narrowed and thinned toward an extreme end, forming an inclined surface on its inside. This construction of the prior art has a problem that the centrifugal force acting on the magnets and vibrations occurring as a result of rotation of the rotor could cause the reinforcing members holding the magnets to shift toward the extreme ends of the claw-shaped magnetic poles, consequently displacing the magnets from their normal positions.